The SystemStartupSetting property indicates the index of the default start profile. This value is 'calculated' so that it ...

The SystemStartupSetting property indicates the index of the default start profile. This value is 'calculated' so that it usually returns zero (0) because at write-time, the profile string is physically moved to the top of the list. (This is how Windows NT determines which value is the default.)

Note:  The SE_SYSTEM_ENVIRONMENT privilege is required on IA64bit machines. This privilege is not required for 32bit systems.